Lubricant deterioration in high speed engines causes the formation of lacquer, and sludge, and carbon deposits on the interior surfaces of the engines, which accelerates wear and reduces engine efficiency. To reduce the tendency for such deleterious products to deposit on the surfaces of the engines, it is known to incorporate in the lubricating oil certain additives having dispersancy and/or detergency properties.
The continuing search for and the necessity of having available ashless dispersant and/or detergent additives for motor oils is well known. Since the development of positive crankcase ventilation systems (PCV) there is a greater demand for improved additives of such types.
Various products have been developed for the purpose of imparting dispersant and/or detergent properties to lubricating oils: such as, by way of example, neutral and over-based metallo-organic compounds such as alkaline salts of sulfonic acids, and of hydrocarbon-P.sub.2 S.sub.5 reaction products. In-service drawbacks of such additives include the formation of undesirable metal-ash thermal decomposition products. Other addition agents were amine salts, amides, and amides of polybutenyl-substituted polycarboxylic acids. Still other proposed additives were combinations of alkaline earth sulfonates and Mannich condensation products of alkyl-substituted hydroxyaromatic compounds, amines having at least one replaceable hydrogen on a nitrogen atom; and aldehydes; alkaline earth salts of such Mannich condensation products have also been proposed.